A gas turbine is composed of a compressor, a combustor, and a turbine. The compressor compresses air, taken in through an air inlet, into high-temperature, high-pressure compressed air. The combustor produces high-temperature, high-pressure combustion gas by supplying fuel to the compressed air and combusting the mixture. The turbine has pluralities of turbine vanes and turbine blades installed alternately along a passage inside a casing, and a turbine shaft coupled to a generator is driven to rotate as the turbine blades are driven by the combustion gas supplied to the passage. The combustion gas having driven the turbine is released as exhaust gas into the atmosphere.
The gas turbine has a cooling air system (cooling air supply means) in which the compressed air compressed by the compressor is taken out and cooled by a heat exchanger (TCA cooler) etc., and then is supplied to the turbine side, at the interface between parts of a rotating body, including the turbine blades, and fixed parts so as to cool those parts.
Japanese Patent Publication No. 2011-137389 describes a gas turbine cooling flow passage structure having: a plurality of cooling medium flow passages that guide a cooling medium for cooling the rotating body of the gas turbine from a stationary body toward the rotating body and guide the cooling medium in a rotation direction of the rotating body; a cooling medium guide part that serves as a partition between each two of the plurality of cooling medium flow passages and constitutes a wall surface; and a shroud part that is disposed in at least one end part of the cooling medium guide part. The cooling flow passage structure is composed of a plurality of segments each having the cooling medium guide part and the shroud part, with the shape of one cooling medium guide part in at least one segment being different from the shape of the other cooling medium guide parts in the other segments, and the flow passage sectional area of the cooling medium flow passage adjacent to that one cooling medium guide part being different from the flow passage sectional area of the cooling medium flow passages defined between the other cooling medium guide parts.